symlink() creates a symbolic link named linkpath which contains the
string target.
Symbolic links are interpreted at run time as if the contents of the
link had been substituted into the path being followed to find a file
or directory.
Symbolic links may contain .. path components, which (if used at the
start of the link) refer to the parent directories of that in which
the link resides.
A symbolic link (also known as a soft link) may point to an existing
file or to a nonexistent one; the latter case is known as a dangling
link.
The permissions of a symbolic link are irrelevant; the ownership is
ignored when following the link, but is checked when removal or
renaming of the link is requested and the link is in a directory with
the sticky bit (S_ISVTX) set.
If linkpath exists, it will not be overwritten.
symlinkat()
The symlinkat() system call operates in exactly the same way as
symlink(), except for the differences described here.
If the pathname given in linkpath is relative, then it is interpreted
relative to the directory referred to by the file descriptor newdirfd
(rather than relative to the current working directory of the calling
process, as is done by symlink() for a relative pathname).
If linkpath is relative and newdirfd is the special value AT_FDCWD,
then linkpath is interpreted relative to the current working
directory of the calling process (like symlink()).
If linkpath is absolute, then newdirfd is ignored.

EACCES Write access to the directory containing linkpath is denied,
or one of the directories in the path prefix of linkpath did
not allow search permission. (See also path_resolution(7).)
EDQUOT The user's quota of resources on the filesystem has been
exhausted. The resources could be inodes or disk blocks,
depending on the filesystem implementation.
EEXIST linkpath already exists.
EFAULT target or linkpath points outside your accessible address
space.
EIO An I/O error occurred.
ELOOP Too many symbolic links were encountered in resolving
linkpath.
ENAMETOOLONGtarget or linkpath was too long.
ENOENT A directory component in linkpath does not exist or is a
dangling symbolic link, or target or linkpath is an empty
string.
ENOMEM Insufficient kernel memory was available.
ENOSPC The device containing the file has no room for the new
directory entry.
ENOTDIR
A component used as a directory in linkpath is not, in fact, a
directory.
EPERM The filesystem containing linkpath does not support the
creation of symbolic links.
EROFS linkpath is on a read-only filesystem.
The following additional errors can occur for symlinkat():
EBADF newdirfd is not a valid file descriptor.
ENOENT linkpath is a relative pathname and newdirfd refers to a
directory that has been deleted.
ENOTDIRlinkpath is relative and newdirfd is a file descriptor
referring to a file other than a directory.

No checking of target is done.
Deleting the name referred to by a symbolic link will actually delete
the file (unless it also has other hard links). If this behavior is
not desired, use link(2).
Glibc notes
On older kernels where symlinkat() is unavailable, the glibc wrapper
function falls back to the use of symlink(). When linkpath is a
relative pathname, glibc constructs a pathname based on the symbolic
link in /proc/self/fd that corresponds to the newdirfd argument.

This page is part of release 5.01 of the Linux man-pages project. A
description of the project, information about reporting bugs, and the
latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.
Linux 2017-09-15 SYMLINK(2)